Multiple unit radio recorder



- March 21, 1944. J, T. PQ'TTER MULTIPLE UNIT RADIO RECORDER Fi1ed May 18, 1940 2 sheets-sheet 1 BY Mv ATM/wey v J.' T. POTTER MULTIPLE UNIT RADIO REVCORPER mmh 21,1944.

Filedmay 18; 1940 2 Smets-snee; 2".'

1 N VE N TOR .OLILZ Poer 47m/mfr Patented Mar. 21, 1944 i UNITED i STATES PATENT OFFICE Y MULTIPLE UNIT RADIO RECORDER vJohn T. Potter, Brooklyn, N. Y. Application May 18, 1940, Serial No. 335,886

` (c1. zal-1.5)

3 Claims.

The present invention concerns recorders and in particular recorders for recording the tuning and operating conditions of a plurality of radio receivers.

This general type of recorder has been shown in my Patent Number 2,249,324 issued July 15, 1941. Some features of the method of coupling to the radio receiver are shown in Patent Number 2,213,886 issued on September 3, 1940.

One object of the present invention is to simplify the method of and means for recording the operation of a plurality of radio receivers on a single record sheet.

Another object is to simplify the installation of a remote unltat a radio receiver.

Still another object is t simplify and improve the operation of the signal generating unit of the remote unit.V y

A further object'is to provide more reliable operation of the remote unit especially over a long period of time without attention. I

A still further object is to provide a remote unit capable of transmitting a signal to the recorder over a longer distance than hash'itherto been obtainable.

These and other objects of the invention will be evident from the detailed description of the invention givenvin connection with the various figures of the drawings.

Radio broadcasting in this country is largely paid for by advertisers. The effectiveness of this fon'n of advertising is most accurately measured by measuring the size of the listening audience. The determination of the size of this audience has become very important to the4 whole broadcasting structure. Previously, audience measure-y ments have been made by telephone calls" or house to house visiting.. This is an inaccurate, slow and expensive method of determining the audience. Much desired information lbecomes almost impossible to obtainby this method. Machine recording of the operation of .radio receivers has been found to be quickaccurate and cheap.4 One machine can more than replace hundreds of telephone or house to house calls. l

Two general types of machine recorders have been disclosed ln the l'above referred to patent applications. One type has been called a single unit since each recorder records the operation.

of a single radio receiver.l The second type has been called a multiple unit since each recorder records the operation of a number of radio receivers. The present invention particularly concerns multiple unit" recorders.

Briey, the multiple recorder of the type with which the present invention is concerned comprises a number of remote units each lattached to a radio receiver and a central recorder unit. Each remote unit transmits by means of timed impulses information indicating the mode of operation of its connected radio receiver toa central point where a recorder is located. This multiple lrecorder system has the advantages that the mode of operation of a number of radio receivers may be recorded on a single record sheet. These records are convenientlyl collected every twenty-four hours, giving a daily record of the operation of a large number of radio receivers. The present invention concerns an electronic coupling unit which greatly simpliies the 'attachment of remote units to theradio receivers; means for increasing the power output of the remote units permitting a greater radius of operation from the recorder; and various other features which cheapen, simplify and improve the operation of the multiple type recorder.

In the drawings:

Fig. 1y shows a block diagram of one embodiment of the present invention.

' Fig, 2 showsa circuit diagram of a particular form of the present invention.

' Fig. 3 shows a detail of modes of connection of the signal generator to a radio receiver. y

Fig. 4 shows the relation between carrier and oscillator frequencies in a typical superheterodyne radio receiver.

The block diagram of Fig. 1 shows the general layout of one form of the present invention. It shows a superheterodyne radio receiver, the signal generator controlled Iby the oscillator of the radio receiver, and the multiple recorder. The radio receiver may Vbe any conventional radio receiver and in the form shown in Fig. 1 includes a radio frequency amplier marked R, F. amplier for selecting and amplifying the received signals. It includes a rst detector which receives signals from the radio frequency amplifier and mixes them with signals from'a tunable variable frequency oscillator to produce an intermediate frequency signal which is passedon to an intermediate frequency amplifier. The first detector and tunable oscillator are represented by the block marked Det & tunable oscillator and the intermediate frequency amplier by the block marked 1 F. amplifier. The amplified intermediate frequency signals are passed along to a second detector marked Detector. The detected signals are applied to an audio frequency amplier marked Audio amplifier" the output of the operation of the a number of signal ge sending signals over the power is luy-passedv by conde coupling condenser III.-

v This is particularly ,p L. which is connected to a loud speaker marked Speaker. Power to operate the various units of the receiver is derived fromy a power line as, for instance, a 110 volt, 60 cycle line and is passed through suitable rectifiers and filters 5 marked Power supply.

In order to generate signals characteristic of bove described radio re ceiver, signals from the oscillator of the receiver are applied to a selective system including an amplifier stage and two tuned circuits. The circuits are tuned in timed sequence to a plurality of oscillator frequencies, the presence of any one of which indicates that the radio receiver is tuned to one of a plurality of predetermined radio sta'- 15 tions which fact it is desired to record. One way to tune the circuits thru the desired sequence is to operate a step selector by means of a synchronous motor connected to the 110 volt, 60 cycle source. The selector is shown as Adjustableselector and the synchronous driving motor as Motor. The selected signal is [fed to a, detec- .tor marked Detector which generates an impulsewhich in turn is fed to a signal control circuit marked Control circuit." 'Ihe signal con- 25 trol circuit when it receives an impulse from the detector energizes a signal generator as, for instance, a 20 kilocycle oscillator and output amplifier marked Signal generator. The 20 kilocycle signal is applied to the power line over which it travels to a recorder at some remote point marked Multiple recorder." This recorder is called a Multiple recorder since the signals from a large nerators as described above a single recorder. A suitable recorder is shown and described in the copending application entitled Multiple recorder" Patent Number 2,249,324 issued July 15, 1941.

In Fig. 2 is shown a preferred form of the present invention attached to a radio receiver and line although it the signals may evidently other wires such may be .recorded by is not so limited since be sent thru the ether or over as telephoneA or telegraph lines. A radio receiver I is shown connected to antenna 2 and ground 45' 3. The signal generating system includes an input signal amplifier tube 4,v a detector tube 5, n an oscillator control tube 6, a signal oscillator 1, an output signal amplifier 8, and a rectiiier 9 for supplying power to the signalgenerator. Input amplifier tube 4 is a pentode having a cathode I3, control grid I4, screen grid I5, suppressor grid I6 and plate I1. Cathode I3 receives a bias from cathode current drop in resistor I8 which nser I3, Screen grid I5 55 receives a bias thru dropping resistor 2I and is by-passed by condenser 20. Suppressor grid I6 is connected to cathode I3. Control grid I4 is connected to the secondary I2 of input trans former II-I2. Primary II ls connected to the oscillator of the radio receiver I by means of It has been found thaty mail capacity of the;`

condenser III may be a very s order of 1 micro-microfaradV if litl is connected to a point in the oscillator circuit having a` subm5l stantial radio frequency voltage to ground. 'This capacity may be varied to suitthe particular receiver or the particular point of connection and in each case is made small enough not to disturb thel calibration or tuning point of the receiver.

important in the case of ivers where it is desirable to ithout retuning the push-butpush-button rece connect the unit w ton adjustments.

The periodic selecting system shown'in Fig. 2 75 ing vcontacts by connecting secondary .able bias point on voltage divider 53.

l each time contactors and plate 51' yi'sthe Controlled lltp voltag includes two commutators 24 and 31. Each segment of these commu-tators is insulated. from the others and from ground and is connected to individual and adjustable condensers 25 and 38. Contact with the commutators is made by slid- 26 and 21. These contacts are moved over the commutators in a predetermined man-y ner by means of rod 28 biased by a tension spring 28' against cam 30 which is driven by the synchronous motor 93 from the alternating current power line. Cam 30" is thus rotated and moves contactors 26 and 21 over commutatore 24 and 31 in a predetermined manner. Condensers 38 are adjusted to tune secondary I2 to a plurality of predetermined oscillator frequencies each corresponding to a carrier frequency, the reception of which'by the radio receiver it is desired to record.

Ampliile and having its plate of transformer 22-2 them on. `Secondary 23 densers 25 at any given position. of contactors 23 and 21 to the same frequency as that to which secondary I2 is tuned and thus further selects desired signals. The desired signal thus selected and amplied is rectified by diode detector 5 23 to plates 42 and 43 tied together and to cathodes 4I and 44 thru load resistor 39 by-passed by condenser 4'0., The system thus far described generates voltage impulses across resistor 39 corresponding to selected desired oscillator signals. The cathode end of resistor 39 is positive and is connected to control grid 49 of control tube 3. Cathode 48 is con nected thru relay coil 41 and jack 5I -to a suit- Relay .45-,46-41 is normallyA open at contact 46'and the impulses on grid 49 cause it to close partially completing ak circuit between the return circuit of oscillator 1 and ground 3. Relay 41 operates 26---21 contact condensers tuning the system to an operating oscillator frequency. 4It is desired, however, to operate oscillator 1 only when contact is made on the steel part of cam 39 in order'that signals may only begenerated during short predetermined interI vals.V In ordervto make these intervals less fre quent the `generation of oscillator signals ma; be limited to every 2nd, 3rd or 4th revolutioi of cam 39. .To accomplish this a conducting seg ment 34, which covers one-eighth of the circum ference of its circle, closes the circuit betweer r tube 4 thus receives selected signals I1 connected to primary 22 3 amplifies them and passes is tuned by one of con- "contacts 35 and 3B during the desired interval completing the return circuit of oscillator Segment 34 is carried by an insulating disc 3 geared to motor 93 by means of'gears 3I and 3. For instance. M gear 32 has four times the mm bero! teeth of gear 3|, the circuit is close throughout one half of every fourth revolutie of cam 30. v .g i Tube lincluding `cathode 85,1control grid l y y ysignalgene: ating oscillatortubel j Itsj circ'uitifncludes grid cc 1 6.4 coupled'r topl'ateoil'. Plate coil "62 vis tum `to 2 0f1kilocyclesbyxneansif f lable-f condens 63. Feed-back isobtainedy by icoznrf'cting lcoil t0 plate "31 1 thru blocking 'condens 'A Band feel back control! resistor '68. lThe.o.'lrcillation wa form may be improved Icy-means `off-the un-b passed degenerative Aca'aithode"ifes'istor'f I I0. Pla eis supplied thru'. theparallel-feed cho 10. 4Thecircuit-will osciuate chlyif the 1 side .of the circuit'is completed to ground 3 th contacts 35-36 and 46.

-r of the receiver.

, Oscillator 1 thus generates 20 kilocycle signals in accordance with the receiver tuning and the timing circuits. The 20 kilocycle signals are amplied by outputl tube 8 which comprises a double triode connected in push-pull.` One triode includes cathode 16, control grid 11 and plate 18 `while the other triode includes cathode 19, control grid 80 and plate 8|. The 20 kilocycle signals are applied vto grids 18 and 80 by means of the A push-pull input transformer 12-13. Condensers 14 and 15 connected across secondaryA 13 are used to at least partially tune secondary 13 to improve the waveform of the output and to increase the input to tube 8. Plates 18 and 8| feed primary 82 of the push-pull output transformer 82-83. The primary 82 may be tuned by condensers 94 and 95 also to improve the waveform decreasing the possibility of harmonic interference and toy vmotor 93 is operated continuously to maintain its phase relation with other signal generators in the system, the power is turned on to the remaining part of the unit by means of relay 9|. Relay 9| is normally held Open by means of spring 90 opening contact 89 in series with the power supply. The power line current to the radio receiver is passed through coil 92 and hence whenever the receiver is turned on coil 9| is energized attracting armature 88, closing contact 89 and thus supplying power to the unit.

In case the receiver is operated on a station which is other than those which it is desired to record, it is still desirable to record the operation 'Ihis is accomplished by means of contacts 85-8lil connected across contact 46 and closed once for each revolution of the cam 30 by means of point 81 on rod 28. Thus a signal is generated independently of the tuning of the radio receiver indicating that it is being operated.

Fig. 3 shows one method of connecting the signal generating unit of Fig. 2 to the oscillator of a superheterodyne receiver and suggests three a1- ternative connections. Other modes of connection will be evident to those skilled in the art. Tube 96 represents the oscillator tube' of a typical superheterodyne radio receiver such as the one shown in Fig. l. Oscillator tube 9-6 is shown as a triode having a plate 99, a grid 98, and a cathode 91 heated by well known means not shown. The oscillatory circuit from grid 98 to cathode 91 includes gridy resistor v|| bypassed by .grid condenser-|00, and grid coil |02 tuned .by trimmer condenserl |04 and tuning condenser |06 in series with padding'lcondenser |05. Feedback to provide oscillation is furnished by means of plate coil |03 coupled -toigrid'coil |02 connected between plate 99 and bylpass' condenser |01. Coupling condenser l0fwhicli couples` the oscillator to the signal generatingfunit is shown connected to plate 99. One of the most convenient methods of conne'ction lis to place the connecting-wire to convsuperheterodyne radio receiver as shown in Fig. 1.

Condenser |09 may be ganged with condenser |06 as represented by the connecting dotted line.

Coil |08 is tuned to various desired carrier frequencies .by condenser |09 while the oscillator coil |02 is tuned to a frequency which is higher or lower 4by the desired intermediate frequency. Fig. 4 shows the relation between carrier frequencies and oscillator frequencies in a superheterodyne having an intermediate frequency of 500 kilocycles and a carrier frequency range of 500 to 1500 kilocycles (0.5 to 1.5l mC.). AThis dagramshbws, for example, that when receiving a carrierfrequency of 1 mc. that coil |08 is tuned by condenser |09 to l mc. while the oscillator tu-be 96 oscillates at 1.5 mc. as determined by the tuning of coil |02 by condenser |06.

- Returning to the operation of the vsignal generating system of Fig. 2, in order to generate a signal indicating operation ofthe receiver on this l mc. frequency one of condensers 38 and the correspon g condenser 25 are set to tune coils I2 and 23 respectlvely to 1.5 mc. so that the signal from oscillator tube 98 thru condenser lIll being 1.5 mc. will cause a signal to be generated by oscillator tube 1. ,Thus the signal generating system is responsive to one frequency while the receiver is tuned to another. The signal generator produces a signal indicating operation of the receiver on ar particular carrier when the os cillator of theyireceiver oscillates at a predetermined frequency difference from the carrier. The same relation holds for generating signals indicating operation on other predetermined carriers. This relation of response frequency of the signal generator to carrier being received by the receiver will be the samefor all the signal generators in the system operating on receivers having the same intermediate frequency and in which the oscillator is on the same side of the carrier. The relation will be different for receivers employing the same intermediate frequency but with the oscillator on the other/ side of the carrier. The relation will also differ for different intermediate frequencies. Thus one multiple recorder may record the operation of a large number of radio receivers on a predetermined selection of stations while the signal generators comprising the system may be responsive to many different frequencies as determined by the intermediate frequencies of the receiversto which they are connected.

It should be noted Athat the signal generator will operate with any type of superheterodyne radio receiver equally well. Push-button receivers, inductance tuned receivers, automatically tuned receivers, remote control receivers, midgets and in fact any type of superheterodyne may be used in connection with the signal generator shown. An all-wave receiver automat-A ically registers when actually operating on the carriers'selected and automatically cuts-off on other wave bands due to the lack of the proper oscillator frequency. Similarly, the 'device is not limited to the broadcast band.y or any one band. For instance, three stations in the broadcast band may be recorded, two in the frequency modulation band and two in the television band merely by proper choice of coils |2 and 23 and condensers 25 and 38.

While` only a single embodiment of the presen't invention has been shown and described, many modifications will be apparent to those skilled in the art ywithin the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a radio receiving systemA for recording the operation of a radio receiver, the combination of.

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and adaptedvt'e:levconnectedf'toax signa-l; carrying: circuit' off' sad nadiul receiven. am impulse signalA41 generatori' fm1. prodiicing: a1 marking@ signril 'orf a'. remote recondeir-iii: resp'cmse,` be: selected? signals traversing said amplifier; andi ,meansfor di'szi'blingi` sa'i'd generatori d'uni'ng the cyclev ofi op`- eration. of." sa'i'd contacten betweem the: times ofi selecte'd pexfeds o'f contacting. saiidi contactisv..

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t selecdzsignanoumueoffsaidampueenfneciosingg said: relay: i i

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